All emails sent to 'root' are forwarded to that address. So, apt notices, etc. The email address is stored in /etc/pve/user.cfg
Curious, what KVM are you using? I've installed Proxmox via iLO, DRAC, IPMI, and Avocent KVMs many times, without issues.
apcupsd isn't a web server, so it won't work from a browser. If you want a web interface for it, you'll need to setup a web server running the apcupsd CGI scripts, http://www.apcupsd.org/manual/manual.html#apcupsd-network-monitoring-cgi-programs
Probably best to upgrade to latest Gluster 3.7, or 3.8 from the Gluster repo. I recall some fixes recently related to issues with ZFS based bricks. That said, RedHat currently only recommends XFS for bricks.
This is what /etc/network/interfaces looks like on one my hosts.
auto lo
iface lo inet loopback
auto vmbr0
iface vmbr0 inet static
address 192.168.1.10
netmask 255.255.255.0
gateway 192.168.1.1
bridge_ports eth0
bridge_stp off
bridge_fd 0
FWIW, Proxmox with kernel 4.4.10 detects the E5-2698 V4 CPUs that are in one of my boxes. And correctly indicates they have 20 cores.
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 79
model name : Intel(R) Xeon(R) CPU E5-2698 v4 @ 2.20GHz
stepping : 1...
What's the file system type of the physical disk? I'm curious as your fdisk output is showing "Microsoft basic data" for the partition type, and I'd expect that to say Linux.